1. Field of the Invention
The invention relates to a recording and/or reproducing method of recording and/or reproducing predetermined data to a recording medium on the basis of a command which is sent from a host computer through an SCSI (Small Computer System Interface).
2. Related Background Art
SCSI is an interface which has been deliberated in the X3T9.2 Work Committee of ANSI (American National Standard Institute) on the basis of the interface SASI (Shugart Associates System Interface) for connecting a small computer and its peripheral apparatuses made by Shugart Co., Ltd. in the U.S.A. and has been standardized as ANSI X3.131-1986. The SCSI is at present becoming a standard interface for connecting a personal computer and its peripheral apparatuses. In recent years, the work to standardize SCSI-2 as an expanded version of SCSI has progressed. A final decision of SCSI-2, however, has not yet made at the present point in time. There are the following five ranges of the SCSI interface rules which are specified by the ANSI.
(1) The kinds and definitions of interface signals and timings for transmission and reception of the signals.
(2) A protocol to specify the operation sequence as an interface and definitions of phases and the like.
(3) Physical interface conditions such as cable specifications, connector specifications, and the like, and electrical conditions of the transmitting system.
(4) Command systems to execute various controls of peripheral apparatuses and data transfer, formats of commands, functions of commands.
(5) A status byte format to inform the result of execution of the command to a host computer, and a structure of sense data to inform an abnormality state or the like during the execution of the command.
The command system in the above item (4) is as follows. First, an SCSI command is classified into eight kinds of groups. The first byte of a CDB (Command Descripter Block) indicates an operation code. Upper three bits of the first byte designate a group code and lower five bits designate a command code (code indicative of the kind of command) of each group. A length of CDB is specified for every group in the following manner.
______________________________________ (1) group 0 6 bytes (2) group 1 10 bytes (3) groups 2-4 reserved (4) group 5 12 bytes (5) groups 6-7 vendor unique (specified by the manufacturer) ______________________________________
The CDB of groups 6 and 7 is a group of commands which can be defined so as to be unique to the SCSI device. In each command, a logic block address is constructed by continuously arranging data blocks each having a fixed length on a logical unit.
FIG. 1 is a diagram showing a construction of a logic block in a hard disk device. In FIG. 1, a data block of a cylinder=0 and a sector=0 is set to a logic block address=0. The logic block address is increased by "1" each time each of the sector, track, and cylinder is increased by "1" in accordance with this order. An excellent point of the logic block address is that there is no need to be aware of a physical structure because an initiator (host computer) designates the logic block address of the first data block and the number of processing blocks and accesses the data. When the logic block addressing is used, therefore, in the case where the devices in which the number of cylinders, tracks, sections, and the like are mutually different are connected, they can be made operative by the same software.
FIG. 2 is a diagram showing a general example of a system construction of SCSI. As a logic unit, generally, as shown in FIG. 2, there are many cases where a physical device such as a hard disc or the like is connected. The logical unit number (LUN) can be assigned to the physical device or also can be assigned to a virtual device. In SCSI, ordinarily, eight logic units of LUN=0 to 7 can be connected to an SCSI bus. Further, by using an expansion message, up to 2048 logic units can be connected.
On the other hand, as an information recording medium, hitherto, a floppy disk to magnetically record and/or reproduce information, an optical information recording medium to optically record and/or reproduce information by using light, and the like are known. Various types such as disk shape, card shape, tape shape, and the like are known as a form of the optical information recording medium. Among such optical information recording media, the card-shaped optical information recording medium (hereinafter, referred to as an optical card) is small and light and is conveniently portable and a large demand is expected as an information recording medium of a relatively large capacity. The information recording medium is mainly classified into a type in which information can be erased and rewritten and a type in which the recorded information cannot be erased and rewritten in accordance with the characteristics of the medium. In general, the information of the optical card cannot be erased and rewritten, so that an application of the optical card is expected in the field such as a medical field or the like in which a fact that the recorded information cannot be rewritten becomes an advantageous.
As mentioned above, on the other hand, since the optical card is generally of the unerasable and unrewritable type, for instance, in the case where directory information or the like which ordinarily consists of several tens of bytes is recorded onto the optical card in which-a data capacity of one track is equal to 512 bytes or 1024 bytes, the remaining portion of one track becomes vain and the data capacity cannot be effectively used. Therefore, there is also proposed an optical card in which a plurality of sectors can be recorded on one track. In such an optical card, a plurality of sector types of different data capacities are prepared. For instance, in a case of the sectors such that a data capacity of one sector is equal to 1024 bytes, one sector is arranged in one track and is used for data recording. In a case of the sectors such that a data capacity of one sector is equal to 32 bytes, 12 sectors are arranged in one track and are used for recording a directory. Due to this, the information capacity of an optical card can be effectively used. In the SCSI system, however, there is a rule such that when information is recorded and reproduced by using the logic block address mentioned above, the logic blocks are handled as the same size (capacity). Therefore, the sectors in which data capacities (sector sizes) per sector differ as in the above optical card cannot be collectively used. Recording and reproducing commands also can be obviously prepared as vendor unique commands for every sector size. When the number of kinds of sector sizes is large, however, a number of vendor unique commands to execute the same recording and reproduction as a function exist, so that it is undesirable from a viewpoint of the compatibility with the other devices.